Active surveillance in metastatic renal cell carcinoma: A single-center cohort.

Abstract

389 Background: Emerging data suggest that active surveillance (AS) may be safely implemented in a subset of patients (pts) with metastatic renal cell carcinoma (RCC) and indolent disease to delay the initiation of systemic therapy without undermining long-term survival. However, widespread adoption of AS has been limited by a lack of data on factors portending favorable outcomes. In this study we sought to characterize pts undergoing AS at a large academic medical center to identify factors associated with time on AS. Methods: We identified pts on AS using Kidney Cancer Explorer (KCE), the data management platform of the Kidney Cancer Program at UT Southwestern Medical Center (2005-2020), as well as input from medical oncologists. The AS cohort was defined by (1) having metastatic RCC (determined by either a suspicious lesion > 1cm or a positive biopsy), and (2) the absence of prior systemic therapy. Baseline characteristics and IMDC criteria were evaluated at the outset. Outcomes of interest included progression free survival (PFS), time to systemic therapy (TST), and overall survival (OS). Survival estimates were generated using Kaplan Meier methods. Cox proportional hazard models were used in univariate and multivariate analyses to identify baseline characteristics associated with TST. Results: We identified 37 pts with metastatic RCC undergoing AS; 31 pts (83.8%) had ccRCC, 28 pts (75.7%) had a favorable IMDC prognostic group, 18 pts (48.6%) had one metastatic lesion at baseline, and the cohort had an average tumor burden of 21mm. The majority of pts had clinical or radiologic progression with a median PFS of 10.8 months (95% CI: 8.13-23.31). The median TST was 37 months (95% CI: 24.3-94.9). In total, there were 11 deaths (none of which occurred prior to the initiation of systemic therapy) and median OS after the initiation of AS was 132.5 months (95% CI: 87.3-NR). Multivariate analyses showed that higher numbers of metastatic lesions at baseline were associated with a shorter TST (HR:1.45; 95% CI: 1.03-2.03, p = 0.03). At a median follow-up of 62.5 months, 11/37 (29%) of pts had not yet started systemic therapy. Conclusions: These results expand upon previous studies and support a role for AS to delay systemic therapy in selected pts with metastatic RCC.